Lock seam



Sept. 27, 1949. ,1, [NGELS 2,483,095

LOCK SEAM Filed April 9, 1947 A 5 W 23 I)? a f 20 2/ /0 l9 8 Inventor.-

Patented Sept. 27, l949 STATES PATENT OFFICE LOCK SEAM James J. Ingels, Chicago, Ill.

Application April 9, 1947, Serial No. 740,457

- 3 Claims. 1

My invention relates to a lock seam between two edge portions of the same sheet or different sheets of material such as metal. The seam is one which may be easily produced and operated to locked position. It may also be unlocked whereby to release the two edge portions, in case such an end be desired.

The lock seam herein to be described provides a pair of spaced beads one on each side of the seam, these beads being a part of the seam and constituting a stiffening reenforcement for the joined edge portions. The seam thus provided is also attractive in appearance, it does not project appreciably beyond the exposed surface of the edge portions which are thus united, and it provides a degree of resiliency, with capacity for movement of the seam elements under pressure, sufiicient to permit a release thereof in response to proper manipulation.

A lock seam having these various characteristics and capable of achieving the objects noted may be embodied in a construction such as the one herein illustrated wherein:

Figure 1 is a view in perspective of one end of a pipe or conduit having the meeting edge portions thereof united by the present lock seam;

Fig. 2 is a fragmentary end elevation, enlarged, of the two edge portions of a sheet or sheets which, when joined, form the seam of this invention; and

Fig. 3 which is a similar View shows the two edge portions joined to produce my improved seam.

In the exemplification shown in Fig. 1 there is a short length of pipe or conduit which is desirably produced from a metallic sheet S (usually of steel) whose opposite edge portions, after being specially formed, are united by the present lock seam. For convenience in designation, one of these edge portions is designated as A, and the other as B. As by suitable dies or rolls there is formed in the edge portion A a slight angle at 5 beyond which the sheet is folded at 6 to provide a first bead which normally outstands slightly beyond the arc or plane of the remainder of the sheet. From the fold 6 the edge portion continues through a section 1 to join with a second fold 8 which is faced reversely to the fold 6, there being beyond this fold a slight angle 9 where it joins with a tongue II] that extends along the sheet edge. The section 1 and tongue l0 standing in acute angled relationship constitute a tension head which when free and unconfined occupies a position about as indicated in Fig. 2.

The other edge portion 13 of the sheet S is slightly angled at l5 beyond which it is continued through a fold [6 to provide a second bead which joins with a section I! which at I8 is reversely folded. At this point the edge portion continues on through another section H! which joins with a fold 2G to connect with a section 21 having at 22 a reverse bend in connection with another section 23. The two sections 2| and 23 which are united by the reverse bend 22 constitute in effect a two ply section which extends along the sheet edge. By the configuration thus provided for the edge portion B, there is formed, in effect, a dovetail channel having opposite converging sides defined by the sections l1 and 2! which are united to the base section I9 which, as shown, is arched inwardly to a slight extent.

Two edge portions A and B of the same or different sheets are adapted to be joined securely and immovably, yet releasably, when the tension head of the edge portion A is fitted within the dovetail channel of the edge portion B. For this purpose the tongue in is first advanced edgewise over the reverse bend 22 and then fitted into the angle between the sections H and I9 and close to the inside of the fold 18 at the base of the channel. In executing this movement, the angle-fold 8 of the head may be passed over the reverse bend 22 which is at the channel top, and when past that point the angle-fold of the head is free to enter into the dovetail channel to lie to the inside of the channel section 2| which is reenforced by the second ply section 23. The reverse bend 22 is then positioned between the section 1 (constituting one section of the angle head) and the body of the sheet S, the latter opposing any but a very limited opening up of the dovetail channel. With the parts thus disposed, the angle head of the edge portion A will be sprung inwardly very slightly to be retained fixedly within the slightly expanded dovetail channel of the edge portion B. When so expanded the base section l9 tends to arch upwardly and press tightly against the head section [0. The slight angles close to the several folds tend to become slighter when the head is interfitted with the channel. This interlock is in nowise dependent upon the contour of the sheet or sheets S remote from the edge portions A or Bthey may be curved as in a pipe or conduit, or be flat or angled as in other fabrications. Each edge portion is maintained slightly under tension so as to resist any relative movement and prevent any separation of one from the other.

Should it be desired at any time to disconnect the two edge portions thus locked together, this may be accomplished by a proper manipulation of one relative to the other. For this purpose the tongue 10 is advanced further toward the fold l8 thereby permitting its fold 8 to slide along the section 21 in this movement the fold 8 applies to the base section 19 of the channel a pressure tending to flatten its arched contour. A sufiicient clearance is thereby provided for the fold 8 to slide past and over the reverse bend 22 at the top of the channel, whereuponthe angle head of the edge portion A is free for disengage ment from the dovetail channel of the edge por tion B.

A main advantage of the present lock seam is that the two edge portions, when interengaged j sist any relative motion therebetween. When so interlocked. there exists between their two beads 6 and is a slight gap. These two heads u'pstand slightly from the adjacent surfaces of the edge portions A and B so as to present an attractive andsmooth appearance to the seam. Moreover, because they comprise in each case a bend of substantially 180-, there is provided a. stiffening reenforcement lengthwiseof the seam. which will prevent denting or distortionof the two connected edge portions. This is important, particularly in case the seam is ever to be broken to. permit separation of the two connected edge portions.

I claim:

1. A sheet metal structure comprising two interlocking edge portions oneof which is formed into a dovetail channel havin side sections convergin outwardly. from a relatively fiat base and the other of which 'is formed into an angle head adapted for tensioned interfitting with the channel'and, dimensioned to exert pressure against the converging side walls of. the channel and spreading the same and arching upwardly the base thereof into compressing engagement with the angle head and tensioning the same, whereby the channel and the head are held against relative movement.

2. A sheet metal structure comprising two interlocking edge portionsone-of which isformed into a dovetail channel having side sections converging outwardly from a relatively flat base and the other of which is formed into an angle head adapted for tensioned interfitting with the channel and, dimensioned to exert pressure against the converging side walls of the channel and spreading the same and arching upwardly the base thereof into compressing engagement with the angle hea and tensioning the same, whereby the channel and the head are held against relative movement, and each edge portion adjacent its head or channel, as the case may be, being formed with an outstanding bead adapted to lie proximate to the other bead.

3. A sheet metal structure comprising two interlocking edge portions the first of which is are maintained under slight tension so as to reformed into a dovetail channel having side sections, one single and the other double, both converging'outwa'rdly from a common base and the singleside section at its point of juncture with the edge portion being rounded outwardly to provide an outstanding head, the second edge portion beingformed into a head including two sections joined in angular relation and -one of these sections at its point of juncture with the edge portion being. rounded outwardly. to 'provide a second outstanding, head, the angle head being adapted for tensioned interfitting with the channel and dimensioned to exert an outward pressure. against. the converging side sections thereof. and effecting a spreading of said side sections and an upward flexing of the base into compressing engagement with the angle head and. tensioning the latter with the bead of the headlying proximate to the bead of the channel.

' JAMES J. INQELS.

file of this patent:

nwrap STATES PATENTS Number Name Date 1,153,204 Edwards Sept. 14,,1915 133915974 Hayman Jan. 5, 1932 Re. 18AM Krantz Apr. 26, 1932 

